PB2225: ENVIRONMENTAL MODIFIERS OF SEVERITY IN CHILDREN WITH SICKLE CELL DISEASE: A FEASIBILITY PILOT STUDY
Authors: J. Strouse, U. Obdodo, H. Stapleton, D. Thompson
Journal: HemaSphere (2022)

Background: Sickle cell disease is a severe hemoglobinopathy that affects approximately 40,000 children in the United States and over 300,000 infants worldwide each year, mostly in Africa and India. Environmental factors including air and other sources of pollution and weather are potentially modifiable factors that are associated with disease severity in children and adults with SCD in ecological studies of exposure. Our overarching hypothesis is environmental factors such as air pollution, weather, and chemical exposures modify disease severity in children with sickle cell disease. Aims: To evaluate the feasibility of measuring individual exposure to air pollution and other toxins and morbidity in children with sickle cell disease To describe the prevalence of exposure to brominated flame retardants, organophosphates, polyaromatic hydrocarbons, polychlorinated biphenyls, pesticides, and phthalates in children with sickle cell disease. Methods: We enrolled participants with sickle cell disease between 5 and 18 years of age in a prospective study of environmental exposures. We collected information on exposure by questionnaire, biospecimens (saliva, venous blood), and silicone wrist bands worn by the participants for 5 days. We extracted polycyclic aromatic hydrocarbons and other semi-volatile organic compounds from the silicone wrist bands and characterized the compounds by gas chromatography-mass spectrometry. We measured salivary cotinine using a highly sensitive quantitative enzyme immunoassay (Salimetrics, Carlsbad, CA). We collected information on acute health utilization [ED visits, hospitalizations retrospectively (2 years) and prospectively (6 months)] and laboratory results from the electronic health record. Results: We successfully consented 30 (86%) of the 35 patients approached for the study. Our 30 participants were 60% female with a mean age of 12.5 ±3.6 years and hemoglobin of 8.7 ± 1.5 g/dL. Most (84%) had homozygous sickle cell (HbSS), 13% were compound heterozygotes for HbS and C (HbSC) and 3% had sickle beta null thalassemia. Almost all (90%) were treated with hydroxyurea, 10% with voxelotor, and 3% with crizanlizumab. We successfully collect blood and saliva specimens on all 30 participants and completed surveys on 17 (57%) of participants. We identified salivary cotinine levels consistent with environmental tobacco smoke exposure (1 – 20 ng/ml) in 11 participants (44%) and primary tobacco use in 1 (4%). We received 25 of 30 silicone bands from the initial visit (83%) and identified a high prevalence of exposures to multiple chemicals. Image:Summary/Conclusion: This study confirms the feasibility of individual level measures of indoor and outdoor chemical exposures using saliva and silicone bands in children with sickle cell disease. We identified substantial levels of exposure to tobacco smoke and multiple classes of chemicals from other consumer products, furniture, housing materials, and air pollution that may influence the severity of sickle cell disease. We plan to assess the relationship among these exposures and severity in future studies.